O26.91 Pregnancy related conditions, unspecified, first trimester

Billable ICD-10-CM code, FY2026.

MS-DRG index

Defines the logic of DRG(s) 817-819 in MDC 14.

Approximate ICD-9-CM (GEMs)

• 646.81 Other specified complications of pregnancy, delivered, with or without mention of antepartum condition (approximate)
• 646.83 Other specified complications of pregnancy, antepartum condition or complication (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Maternity diagnoses (age 9 through 64): Age conflict edit. These diagnoses are clinically expected only in patients age 9 through 64.

Code annotations containing back-references to O26.91

Back-references to O26

• Type 1 Excludes: Z03.7 Encounter for suspected maternal and fetal conditions ruled out ("known or suspected fetal anomalies affecting management of mother, not ruled out (O26.-, O35.-, O36.-, O40.-, O41.-)")

Nearby codes

• O26.892 Other specified pregnancy related conditions, second trimester
• O26.893 Other specified pregnancy related conditions, third trimester
• O26.899 Other specified pregnancy related conditions, unspecified trimester
• O26.9 Pregnancy related conditions, unspecified
• O26.90 Pregnancy related conditions, unspecified, unspecified trimester
• O26.91 Pregnancy related conditions, unspecified, first trimester (this code)
• O26.92 Pregnancy related conditions, unspecified, second trimester
• O26.93 Pregnancy related conditions, unspecified, third trimester